1. To be entirely out of funds; even to the point that some might argue that it's insane how out of funds you are.
2. To not only be out of funds, but to know that your next incoming paycheck will be entirely dedicated to bills.

Person 1: Wanna catch a movie?
Person 2: Nah, man. I'm broke as a joke.
Person 1: It's cool, I'll cover you and you can pay me back next time.
Person 2: Appreciate it, but I can't. I'm two months behind on rent as well. I'm broke as bananas.